This invention relates to an injection molding machine for synthetic materials and is of the type which has an injection molding unit which, by means of a hydraulic drive cylinder may be inserted on and withdrawn from an injection mold assembly held in a mold closing unit. The machine further has a hydraulic injection cylinder which imparts axial injection strokes to a rotary feed screw which is axially displaceably accommodated in a plasticizing cylinder of the injection molding unit. The injection molding machine further has a carrier block which is provided with a bore for receiving the rear terminus of the plasticizing cylinder. The carrier block is equipped with a supply device for the synthetic material and a mechanism for an axial immobilization of the plasticizing cylinder in the carrier block. There is further provided a low-friction supporting assembly on which the plasticizing cylinder is supported during its insertion into or its removal from the injection mold assembly.
In a known injection molding machine of the above-outlined type, as disclosed, for example, in German Offenlegungsschrift (non-examined published application) No. 1,554,768, the plasticizing cylinder is held for pivotal motion about a vertical axis together with its carrier block and a component of the machine frame supporting the carrier block. Even during the pivotal motion and in the extreme pivotal position the plasticizing cylinder is backed up by a rolling support adjacent the injection mold. A release of the plasticizing cylinder from the centering supports of the carrier block as part of an automatic injection mold replacement is neither intended nor possible. A separation of the plasticizing cylinder from the carrier block may be effected only by a manual disassembly.
In another known injection molding machine of the above-outlined type, as disclosed, for example, in German Pat. No. 2,907,557, to which corresponds U.S. Pat. No. 4,278,354, the supporting assembly is formed of two shell-like components which are connected to one another by a releasable tightening device. A support ring is displaceably held on stationary columns by means of bilateral, horizontal tightening projections of the shell-like components by means of slide sleeves.
It is further known, as disclosed, for example, in German Offenlegungsschrift No. 3,229,223, to provide the preconditions in an injection molding machine for an automatic replacement (exchange) of the plasticizing unit (formed of the plasticizing cylinder and the feed screw) by means of computer-controlled couplings at the plasticizing cylinder and the feed screw. In such an arrangement, however, the plasticizing cylinder forms, with the carrier block, a structural unit which is intended and adapted for replacement as a whole. For a replacement of the plasticizing unit it is therefore necessary to take off the plastic material supply device from the carrier block and thereafter disconnect and remove the structural unit, formed of the plasticizing cylinder and the carrier block, from the remaining component assembly of the injection molding unit.
It is further known, as disclosed for example, in U.S. Pat. No. 3,068,521, to provide a cover completely surrounding the plasticizing cylinder which may be released from its carrier block only by disassembly.
It is also known to provide the plasticizing cylinder of an injection molding machine with a circumferential groove at its rear terminus for engagement by a coupling device which, however, forms part of a permanent mount and thus may not be releasable by computer control.